Best AR caliber for cast boolits?

[zanemoseley]

So if you were going to build an AR solely to be used for target work with cast boolits what caliber would you use? Would you go with a big heavy guy like a 458 socom or 50 beuwolf since they might be as close to the ballistics of a .45-70.

[paul h]

What range(s) do you plan to do your target work at? It seems that getting top accuracy with cast bullets generally favors the larger diameters, but that's tempered with the added recoil making it harder to get top accuracy.

I'd say based on the 30 calibers being one of the most popular for BR competition, that a 300 BO or 7.62X39 upper would be work persuing for a cast AR rifle. Of course the 35 caliber is also a fine one, but then you'd be looking at some sort of wildcat to deal with the constraints of the AR.

[prsman23]

458 winchester magnum.
:-)
Kidding.
I have fun with the blackout. Good for subs and supers. Not just a one trick pony like some may have you think.

[dragon813gt]

300 Blackout. Others will work but they require more work. I will shoot cast 223 when I have time. There a bunch of rifles at the front of the line.

[Markbo]

.458 SOCOM! There are just a TON of .458" bullets out there as well as molds. The .500s? Just a comparable fraction.

[dkf]

The .458socom is pretty plug and play with cast bullets. That is why I am currently building one. You don't even have to use gas checks in some cases. When I get mine finished I want to try some 525gr (540gr lubed and checked) beartooth piledrivers a member on another forum uses in .458socom for hogs. I see NOE has some nice .460 molds too.

[zanemoseley]

So how bad is a 458 gonna kick the snot outta me? I'd be loading target rounds.

[ipijohn]

Another volte for 300BO using Lee's 312-155 Powder Coated. Shot at around 1950 fps.

[Blammer]

300bo with a slower twist barrel, like 1/10

[dkf]

So how bad is a 458 gonna kick the snot outta me? I'd be loading target rounds.

A good bit more recoil than .223/5.56 but it is not huge.

https://www.youtube.com/watch?v=CvN1BorZgjo

Just keep in mind brass is expensive with .458socom, even more so than .50 beowulf and it uses more powder than a .223 or .300blk. Thus it is not going to be an economical plinker like a .223 or .300blk. The .458 does use standard mags though.

[bruce drake]

I have both a 300BLK and a 7.62x39 Upper and I like them both for ease of getting a good cast load to work.

Bruce

[wcp4570]

So if you were going to build an AR solely to be used for target work with cast boolits what caliber would you use?

Based on your intended use there is no need for either of the big calibers unless you are just set on one of them. The 300bo does for me what your are looking for. The Brass is readily available and is easy on powder to get reasonable accuracy with the Lee 155gr cast. I've been having fun with mine.

wcp

[zanemoseley]

Sounds like the 300 blk may be the way to go. Thanks for all the input.

[dondiego]

No one mentioned the .450 Bushmaster. It delivers 45-70 performance and factory ammo is available. It is legal in the shotgun zone now in Michigan for deer too!

[Moonie]

For just target shooting I'd say 300BO, you can shoot full power with little worry about accuracy issues. We have 2 of them in the family, in addition to a 5.56 and 6.8SPC. The 300BO won't recoil like the big bores, not that they are bad but you can use much less lead in 300BO than those do. Again, you said for strictly target shooting, with the bigger ones you are using an unnecessarily powerful cartridge to kill paper.

[freebullet]

500 Phantom

[zanemoseley]

Since I'm mainly concerned with target shooting and don't mind a heavier gun versus a smaller tactical gun should I consider going to the AR10 platform and shooting .308? That would let me reload slower velocity cast boolits or if I want throw jacketed loads into the mix to get a bit better accuracy and distance.

[trapper9260]

Since I'm mainly concerned with target shooting and don't mind a heavier gun versus a smaller tactical gun should I consider going to the AR10 platform and shooting .308? That would let me reload slower velocity cast boolits or if I want throw jacketed loads into the mix to get a bit better accuracy and distance.

That is what I been shooting in my DPMS 308LR cast beside jacket and it all works for me but I had to make up my own data because the one for cast in Lyman hand book did not work in semi auto guns.

[zanemoseley]

What kind of accuracy are you getting from the cast versus jacketed rounds?

[TMenezes]

I love my 458 SOCOM. The bullet selection and hundreds of mold designs, and various 45-70 based components are awesome. So if your a big bore 45-70 type guy then the SOCOM is awesome. The rocoil isn't bad. My standard A2 stock would start to chew up my shoulder during extended shooting sessions so I put the ACE skeleton stock on it with the optional extra thick butt pad and haven't had any issues since then.

I have very little experience with the 300 BO, but if your just looking for a soft recoil plinker then it might be the way to go.

[popper]

Hard to get slower loads in the 308 due to gas volume needed. Finding a BO with 1:10 or slower is tough. ~500fps difference between the 2, 140 vs 168 gr. For bench target use you will need a good trigger,HBAR and rifle stock. I get near MOA with either, in the BO or 308, I'm not a very good shot. 6.5 is like 243, barrel burners so you can't use the fps with cast. There is a big bore varient of the 6.5 that is supposed to do well.

[zanemoseley]

I noticed the Sig Sauer 716 has a 4 way gas valve that has a normal mode, adverse mode, supressed mode and off mode used for single shot operation. Their manual states not to use the adverse mode for extended periods of time as it increased recoil and stress on the rifle but couldn't that be used to cycle lighter cast loads?

[dkf]

I noticed the Sig Sauer 716 has a 4 way gas valve that has a normal mode, adverse mode, supressed mode and off mode used for single shot operation. Their manual states not to use the adverse mode for extended periods of time as it increased recoil and stress on the rifle but couldn't that be used to cycle lighter cast loads?

The "adverse mode" should help the rifle to function on weaker loads than in normal mode. They are basically over gassing the rifle in "adverse mode".

[captain-03]

I just love my 9mm!!

[CGT80]

What 9mm do you have?

I really like my AR 15 and it seems like 9mm would be a great plinker/short range 3 gun rifle for 100 yards and less. I have a dillon 1050 setup to load 9mm and pistol ammo takes less powder and almost no prep vs. something like 300 blackout.

[wlc]

TO me the two easiest calibers to get into to cast for the AR would be either the 300BLK or the 9mm. You have to weigh the pro's and con's of each to decide what you want/need. I went with the 300BLK as it only necessitated either a barrel or upper swap. I went with a dedicated upper and have been pleased. I Johnny Cash built it during all the craziness that has been going on. I actually got the last barrel that Rock Creek had at the time. I pieced the rest together as time, money and availability allowed. I could've probably bought an assembled upper cheaper, but I got exactly what I wanted this way.

I've only shot an M-16 in 9mm at a rental range. Didn't like it. The change over requires more than just an upper swap. If I had an AR in 9mm I'd probably go with a dedicated rifle all around.

I'm sure the 458 SOCCOM would be a hoot, but it is harder IMHO to get into than the 9 or 300. I would love to have one though.

I've been waiting (and waiting, and waiting..) on the Sig MPX to come out before jumping into the 9mm carbine game. Hopefully that one will come out sometime........ CZ also has a 9mm that's new to the market that looks pretty cool too. It is less expensive than the Sig, but is straight blowback where the Sig is locked breech gas piston driven.

[TCLouis]

As I read your post, 300 Blackout came to mind, and it looks lots of other folks thought the same.

Large range or boolit weights and stingy with the powder use . . . . "What's not to like bout that"?

[popper]

Sig Sauer 716 has a 4 way gas valve Or you can make a rifle with an adjustable GB. 300BO needs a pistol gas port to work reliably with subs, carbine is OK for supers. Haven't seen a carbine length 308 with pistol port, you would need an adjustable block for supers. Rifle length is usually rifle or mid port. I got to ~ 1800 fps using 2400 in the 308 but wouldn't even eject the empties. If you are looking at comp. target shooting, the 'class' you want to shoot may determine what you get, external ballistics reign.

[Moonie]

Or you can make a rifle with an adjustable GB. 300BO needs a pistol gas port to work reliably with subs, carbine is OK for supers. Haven't seen a carbine length 308 with pistol port, you would need an adjustable block for supers. Rifle length is usually rifle or mid port. I got to ~ 1800 fps using 2400 in the 308 but wouldn't even eject the empties. If you are looking at comp. target shooting, the 'class' you want to shoot may determine what you get, external ballistics reign.

With the correct powder a carbine length 300BO functions just fine with subs. AA1680, RL-7 are two that do well in this application. H4895 will also do it but I found the ES a bit high.

[paul h]

Seems like the slightly slower powders with a milder pressure peak might be friendlier to cast as well.

[petroid]

The 300BLK is very economical to load since brass is everywhere and 30 cal molds are common. 1:7/1:8 twist is good for subs but tough on cast boolits for supers. My best results have been 1" at 50 yards around 1750fps with lee 312-155. My research lead me to a pistol length gas system to cycle subs reliably

[wlc]

My upper is a 16" carbine length gas and cycles subs fine. A pistol gas system does give you more options on powders though. I use 1680 mostly. I've tried RL7, 5744, and my latest experiment is with IMR 4227. Haven't got to shoot any of those yet. Was planning on today, but snow needed plowing. At least I got my pistol bullet trap reformed today. Amazing what a snow bank is useful for. In the spring I collect really nice clean bullets off the top of the ground. No digging necessary. :)

Another option for subs would to be to use a fast pistol powder that won't cycle the action and use your AR as a straight pull bolt rifle. I have a stupid quiet load with green dot and a 180gr jacketed bullet that won't cycle at all. Almost hollyweird quiet.

[Markbo]

...snow needed plowing....

Living in SE Texas that is one statement I probably will never use in my entire life. :D

[wlc]

Living in SE Texas that is one statement I probably will never use in my entire life. :D

:) I've plowed more than I ever thought I would too. Plowing snow was a very foreign concept to this Georgia boy when we moved up here. That and temps below zero being "normal".

[petroid]

Another option for subs would to be to use a fast pistol powder that won't cycle the action and use your AR as a straight pull bolt rifle. I have a stupid quiet load with green dot and a 180gr jacketed bullet that won't cycle at all. Almost hollyweird quiet.

I'm with you on that. A few grains of WST under the Lee 230gr boolits gives 800fps and sounds like a pellet gun. Punches through 4x4 posts like butter

[GabbyM]

222 Rem with the standard 1:14" twist barrel.

In my avatar you'll see a CZ 527. Mine is in 222 Rem. It's a sub moa rifle running cast at 2,400 fps. From it's 24 inch barrel. Don't know if the AR will feed a 222 satisfactorily. If it will IMHO the 222 is a far superior boolit shooter than a 223. Although I've had fine luck shooting 223 through 1:12 and 1:9" barrels.

Another one I've had on my fantasy rifle list. Is the 6mm-222 with 14 twist. I already have three different cast boolit molds in 6mm. Would give 30% more bullet weight for anchoring coyote. But with the fur price up the 222 is probably better.


If you did stay with a 223 to save on brass forming or buying 55$ a hundred Lapua 222 brass. Definitely get a 223 Rem SAMI chamber and a 14 twist barrel.

Suppose I could load up an AR mag with 222 then try dropping the bolt on a few to see how well they ride home in a 5.56mm.

[1johnlb]

I see some talking about 1in10 300bo , I've been looking for 1 and can't find anything slower than 1in 8. Someone please point me in the right direction.

[xacex]

I have both the 300 blackout, and 9mm pistol AR's. It is hard to say which one I like more. The 300 blackout has got me under 2" MOA with a cast 125 H/P doing almost 2200 FPS at the 100 yard line, and is cheap to shoot. The 9mm is a tack driver at 50 yards, but 100 yards is a challenge with the red dot i have on it. You cannot beat a cast 9mm Mihec 125 H/P with 4 grains of red dot for a cheap load. With free lead I get scrounging, and free brass I have picked up over the years I load the 9mm for .03 cents a piece! 300 blackout is cheap, but a 32 round stick of 9mm hollow points for under a buck is hard to beat for fun plinking that is easy on the wallet. I want to SBR the lower just so I can put the slidefire stock on it. Since the 9mm uses a blow-back system the rate of fire is real fast, and the recoil is manageable. 300 blackout with the slidefire was fun, but would take several thousand rounds to get good at holding it on target. Add a supressor, and you can have a blast without bugging your neighbors. This guy does 9mm without a slidefire.
https://www.youtube.com/watch?v=GIC8SMttjjo

Or with the slidefire. This dude has the ugly stock. This is what I would like to form 1 next.
https://www.youtube.com/watch?v=T5MIujQFkcY

[GabbyM]

Post above by xacex illuminates one of the reasons shooters chose different calibers and rifles to play the same game. xacex is happy with 2 MOA groups from his 300 BO. Likes the big bullets, rapid fire and it is always easier to see bigger holes in paper at distance. Then who doesn't like kicking up lots of dirt to see where the shots fall on a berm or field. Thing is 2 MOA won't win to many competitive contest. I've never had any trouble or even long workups to achieve sub MOA ten shot groups from my 222 Rem, 223 Rem or 243 AI. Even consider them ideal varmint hunters up to coyote sized animals. I own a couple 30 caliber rifles. But I probably put ten shots down the bores of my 22's and 6mm for every one shot in a 30 caliber. I like the little rifles a lot. Like the economy of lead and powder. Some say 22's are hard to cast. I have found that not to be the case.

My load development for 223 in my two AR-s amounted to pushing the load for my 223 bolt gun into an AR mag and shooting the rifles. They easily out shot M-193 ball in both my 12 twist 5.56mm NATO chambered rifle and my 9 twist 223 Rem chambered rifle. They did however not shoot anywhere close to POI of the jacketed ammo.

[xacex]

Dont get me wrong Gabbym, I like small groups too, but some days I like to just play, and play cheap. I have a Grendel that does VERY small groups, and a .223 that does MOA all day long, but it takes concentration that some days I just don't want to put into it. Target shooting/ plinking is stress relief for me my therapy. You bet when hunting season comes around the ones that shoot the tightest groups come out of the safe. That same pistol AR that shoot under 2 MOA cast at jacketed velocity Shoots jacketed bullets sub MOA. Can you guess which bullet I choose to hunt with? However, it is still enjoyable to get lots of trigger time with it in the off season and be able to ring steel all day long with cast. I like the small boolits, but just cant get them into the same speed class as jacketed like I can with the 300BO.

[popper]

Shot the 1:10 300BO for the first time this morning. 0.5 ATC MOA @ 50, 145gr. PBFN. About 1800 in the 1:7 so the 18" barrel & slower twist should be about the same or better. You probably have to get the 1:10 made for you but it does make a big difference.

[RU shooter]

I see some talking about 1in10 300bo , I've been looking for 1 and can't find anything slower than 1in 8. Someone please point me in the right direction.about two years ago I had a BO 20" 12 twist made for me by a fella down in FL name escapes me now but found him over on ar15.com site. Shot real well with cast heavy or light slow or fast didn't really matter was easy to find loads it likes and functioned with had a carbine length gas system .